Influence of pedogenetic processes on the validity of kaolinite crystallinity indices: A case study of an Amazonian Ferralsol-Podzol soil system with white kaolin

Author(s)

Ishida, Debora Ayumi ^[1] ; Vieira-Coelho, Antonio Carlos ^[2] ; Melfi, Adolpho Jose ^[1] ; Lucas, Yves ^[3] ; Brasiliano Camargo, Joao Paulo ^[4] ; Montes, Celia Regina ^[5]

Affiliation

^[1] Univ Sao Paulo, IEE, Nucleo Pesquisa Geoquim & Geofis Litosfera, NUPEGEL USP, Av Prof Luciano Gualberto 1289, BR-05508010 Sao Paulo - Brazil

^[2] Univ Sao Paulo, EP, Dept Engn Met & Mat, NUPEGEL USP, Av Prof Mello Moraes 2463, BR-05508900 Sao Paulo - Brazil

^[3] Univ Toulon & Var, BP20132, F-83957 La Garde - France

^[4] Univ Sao Paulo, NUPEGEL USP, Av Padua Dias 11, BR-13418900 Piracicaba, SP - Brazil

^[5] Univ Sao Paulo, NUPEGEL USP, CENA, Av Centenario 303, BR-13416903 Piracicaba, SP - Brazil

• Document type: Journal article
• Source: APPLIED CLAY SCIENCE; v. 162, p. 435-442, SEP 15 2018.
• Web of Science Citations: 0

Abstract

Structural defects of kaolinite could be associated with its genetic (weathering, pedogenetic, and hydrothermal) processes. Kaolinite crystallinity indices were evaluated in the context of pedogenetic processes associated with a representative Amazonian Ferralsol-Podzol soil system. This soil system, which is comprised of various types of kaolinitic materials and has a soil dynamics characterized by the progressive replacement of Ferralsols by Podzols, has been evaluated by Hinckley (HI), Aparicio-Galan-Ferrell (AGFI), Lietard (R2), and Amigo (A(001)) ``crystallinity indices{''} and the ``expert system{''} of Plancon and Zacharie (PZ). The results indicate that the complexity of the kaolinite population, which is due to pedogenetic processes, makes it difficult to interpret the usual kaolinite crystallinity indices. In areas where kaolinites are formed under low aggressive conditions (higher pH and lower dissolved organic carbon, DOC) and in equilibrium with the soil solutions, low-defect phase becomes dominant and there is a good consistency between the ``crystallinities{''} provided by each index. However, in areas where kaolinites are formed under highly aggressive conditions (lower pH and higher DOC), the proportion of low-defect phase decreases. This induces changes in the values of the indices, which do not have the same weight from one index to another. (AU)

• FAPESP's process: 11/03250-2 - Quantification and dynamics of carbon associated with deep spodic horizons of Amazon Forest soils, towards possible climatic changed
• Grantee: Célia Regina Montes
• Support Opportunities: Regular Research Grants
• FAPESP's process: 12/51469-6 - Modelling the dynamics of equatorial forest soil deep carbon in changing environments - C-PROFOR
• Grantee: Adolpho José Melfi
• Support Opportunities: Research Projects - Thematic Grants